Carcinoembryonic antigen-related cell adhesion molecule 1a-4L suppression of rat hepatocellular carcinomas.

Carcinoembryonic antigen (CEA)-related cell adhesion molecule 1 (CEACAM1) is a member of the CEA family of immunoglobulin-like adhesion molecules with two major splice variants, CEACAM1(a)-4L and CEACAM1(b)-4S, differing in the length of their COOH-terminal cytoplasmic tail. Both forms are down-regulated in prostate and liver carcinomas relative to normal tissues. We have previously shown in a nude mouse xenograft model that restoration of CEACAM1(a)-4L expression in human prostate carcinoma cells (PC-3) suppresses tumorigenicity, an effect observed with carcinomas from several other tissues but never established for hepatocellular carcinomas.

Two variable regions in carcinoembryonic antigen-related cell adhesion molecule1 N-terminal domains located in or next to monoclonal antibody and adhesion epitopes show evidence of recombination in rat but not in human.

In this paper, we have characterized the structure, evolutionary origin, and function of rat and human carcinoembryonic antigen-related cell adhesion molecule1 (CEACAM1) multifunctional Ig-like cell adhesion proteins that are expressed by many epithelial tissues. Restriction enzyme digestion reverse transcriptase-PCR analysis identified three cDNAs encoding novel CEACAM1 N-domains. Comparative sequence analysis showed that human and rat CEACAM1 N-domains segregated into two groups differing in similarity to rat CEACAM1(a)-4L and human CEACAM1.